Traffic direction control apparatus for use in centralized traffic control systems for single-track railroads



4 Sheets-Sheet F. T. PASCOE ET AL FOR SINGLE TRACK RAILROADS INCENTRALIZED TRAFFIC CONTROL SYSTEMS TRAFFIC DIRECTION CONTROL APPARATUSFOR USE MN ,wwkkm I m g w Em MEN Oct. 31, 1950 Filed Ma 10, 1945 E RRINVENTORS Frank 7? Pascoe and BYAPbuP Jronze THEIR ATTORNEY" Oct. 31,1950 F. 'r. PASCOE ETAL TRAFFIC DIRECTION CONTROL APPARATUS FOR USE INCENTRALIZED TRAFFIC CONTROL SYSTEMS FOR SINGLE mcx RAILROADS 4Sheets-Sheet 2 Filed May 10, 1945 R RTW RNSY w b EG E HEM EN 5 b 8 m Y mp E m2 M mm. 0 ww W m w 72 m 5 m 2 PB F 1% Oct. 31, 1950 F. T. PASCOEEI'AL 2,528,073

TRAFFIC DIRECTION CONTROL APPARATUS FOR USE IN CENTRALIZED TRAFFICCONTROL SYSTEMS FOR SINGLE TRACK RAILROADS Filed May 10, 1945 4Sheets-Sheet 4 FEE 4Z5 0 2% aw 0 %ZEHK G 1:25 114 15 J I]? aim [WE/1?ATTORNEY Patented Oct. 31, 1950 TRAFFIC DIRECTION CUNTROL APPARATUS FOR.USE IN CENTRALIZED TRAFFIC CON- TROL SYSTEMS FOR SINGLE-TRACK RAILROADSFrank T. Pascoe, Carnegie, and Arthur L. Jerome, Edgewood, Pa.,assignors to The Union Switch & Signal Company, Swissvale, Pa., acorporation of Pennsylvania Application May 10, 1945, Serial No. 592,947

25 Claims.

1 Our invention relates to railway trafiic controlling apparatus andparticularly to improved circuits for the control of the direction oftrafiic movement, for use in Centralized Traiiic Control machines forremote control of traffic in track stretches in which traffic may movein either direction.

In Fig. 1 of application for Letters Patent of the United States, SerialNo. 501,254 of H. S. Young, filed September 4, 1943, now Patent No.2,420,579, granted May 13, 1947, there are shown interlocked circuits atthe control ofiice governed by the control levers for the signals whichgovern train movements into the opposite ends of a track stretch so asto prevent interference with train movements in the event of impropermanipulation of these levers and to prevent the reversal of thedirection of traffic except when the single track stretch is unoccupiedand the signals governing entrance of tramc into the stretch are atstop.

An object of our invention is to provide an improved system of the type.described which is arranged so that the interlocked circuits in theoflice are governed to prevent a change in the designated trafiicdirection in a stretch as soon as a control code is transmitted to clearthe signal at either end of the stretch.

Another object of our invention is to provide improved traiiic lockingcircuits for C. T. C. ma-

chines which are arranged to eliminate the un locked interval inexisting circuits between transmission of a signal clearing control codeand receipt of an indication code which results in locking of thetraific direction designating means in the C. T. C. machine.

A further object of the invention is to provide improved equipment ofthe type described which is arranged so that, after a signal clearcontrol code has been transmitted and the trafiic direction designatingmeans has been locked, the operator can regain control of the traiiicdirection designating means only after it has been established that itis proper to permit a change in the designated traffic direction.

Anoth r object of the invention is to provide an improved system of thetype described which incorporates locking means which looks the traiiicdirection designating means as soon as a signal clear control code istransmitted and which releases the trafiic direction designating meanswhen a signal clear indication code is received, or after a signal stopcontrol code has been transmitted and an indi ation code is thereafterreceived from the field station through which the signal is controlled.

A further object of the invention is to provide locking means of thetype described which becomes efiective as soon as a signal clearincontrol code is transmitted, and which is automatically released whenother locking means becomes eiTective.

Another object of the invention is to provide in a system of the typedescribed trafiic locking means in the C. T. C. machine which becomeseffective as soon as a control code is transmitted to clear a signalgoverning entrance of trafiic into a stretch, and which thereafterremains eifective until it is certain that conditions in the stretch aresuch that it is proper for the established traiiic direction to bedisturbed.

A. further object of the invention is to provide improved trafiiclocking means of the type described which employs in the C. T. C. machina traffic locking relay which is operated when a signal clearing controlcode is transmitted to a field station, and which provides means in theC. T. C. machine for operating the signal indication relay when a stopsignal control code is thereafter transmitted so that the locking may bereleased upon receipt of an indication code from th field station.

Another object of the invention is to provide improved means of the typedescribed which is arranged so that operation of the indication lampsgoverned by the signal indication relay will not be altered by use ofthe signal indication relay in conjunction with the traflic lockingmeans.

A further object of the invention is to provide improved trafiic lockingmeans of the type described which is arranged to insure that the lookingis effected before a signal clear control code is transmitted and sothat, if the locking is thereafter released, it is certain that theprescribed operations have been performed.

In practicing our invention we provide in the C. T. C. machine a trafliclocking relay which is picked up upon transmission of a control code toclear a signal governing entrance of tramc into a stretch through whichtraflic may move in either direction. When this locking relay is pickedup, it interrupts the circuit of the traffic designating relay to insurethat it maintains trafiic in the direction designated at the time thesignal control code was transmitted. The indication codes received fromthe field following the signal clear control code release the lockingrelay but cause other relays to lock the traflic direction designatingrelay so that control of the traffic direction designating means isthereafter subject to traffic conditions in the stretch. If anindication code is not received from the field which releases thelocking relay, it may be released by sending a signal stop control codand thereafter receiving an indication code from the field which releases the locking relay but also includes elements which will result inlocking of the trafiic direction designating relay unless it is properfor the operator to have control of the traits direction designatingrelay. In one form of the invention a special auxiliary relay isemployed in releasing the locking relay following a signal stop controlcode, and in another form of the invention the signal indication relayis employed for this purpose.

We shall describe two forms of railway traffic controlling apparatusembodying our invention and shall then point out the novel featuresthereof in claims.

In the drawings,

Figs. 1A and 1B are a diagram of a stretch of single track railwayequipped with wayside signaling apparatus governed by a centralizedtraific control system,

Fig. 2 is a diagram of the circuits in the C. T. C. machine at thecontrol office and controlling the wayside equipment shown in Figs. 1Aand 1B, and

Fig. 3 is a fragmentary diagram showing a modified arrangement ofcircuits which may be employed in the C. T. C. machine.

Referring to Figs. 1A and 1B of the drawings, there is shown therein astretch of single track railway extending, between two passing sidings,the rails of which are divided by insulated joints to form a series oftrack sections IT to BT, in-

elusive, each section being provided with a conventional track circuithaving a track relay for detecting the presence of a train in thesection. The stretch is provided with Wayside signal apparatuscomprising a system of cascade-connected reversible line circuitscontrolled by the track relays and by two manually controllable trafilcrelays EWFSR and GEFSR of the polar stick type at the ends of thestretch. Each line circuit as shown is energized at its left hand end,

for the control of the head block signal 41A or ELB according to theposition of switch 3W, and of the intermediate signals 5L and GL, forauthorizing traific to move in the right to left direction through thestretch. The system may be set up for authorizing tranic to move in theother direction by reversing the trafdc relays ZWFSR and lEFSR, in whichcas each line circuit is energized at its right hand end, for thecontrol of the head block signal ERA or ZRB according to the position ofswitch lW, and of the intermediate signals ER and ER. In thisapplication only the portions of the wayside apparatus essential to theunderstanding of this invention have been shown, these being arrangedsubstantially as shown in the above identified application of H. S.Young. The remainder of the equipment, com prising the apparatus forauthorizing trafiic to move through the passing track area, may likewisebe arranged as shown in this Young application.

As shown the wayside signals are of the wellknown Searchlight type andmay be constructed as shown in Letters Patent of the United States No.1,864,224, issued June 21, 1932, to W. B. Wells.

Each signal comprises a lamp and awinding which when energized operatesa circuit controller and a spectacle frame for placing difierent coloredroundels in front of the lamp. The lamps for the head block signals areconnected directly to the terminals B and C of a local source of currentso that they are lighted continuously, while those for the intermediatesignals are lighted upon the approach of a train, by the release of anapproach relay LAR or BAR, the winding of which is included in th linecircuit system. If energized by current of normal polarity, asillustrated by signal 6L, front contact G closes, and the signal isconditioned to display a green or proceed aspect when its lamp islighted. Each signal energized by current or" reverse polarity, asillustrated by signal 5L, closes a front contact Y, and its lamp iflighted displays a yellow or caution aspect. Each deenergized signalcloses its back contacts G and Y and displays a red or stop indicationwhen its lamp is lighted. The front contacts G and Y of each signalcontrol a repeating relay LPC or RPC which governs the line circuit forthe next signal in the rear, while the back contacts G and Y arechecking contacts which generally are included in circuits governingopposing signals.

At intermediate locations, the signals are controlled directly over theline circuits, and directional stick relays are provided for supplyingcurrent of reverse polarity to the signal for the section in the rear ofan occupied section, in the established direction, in accordance withthe usual practice.

At the end locations, th signals are governed in accordance with trafiicconditions in the stretch by a polarized line relay ZRHD and ALHD whichis included in the line circuit at the entrance end by the reversal ofthe associated traffic relay, and the signals are also governed by amanually governed signal control relay ZRI-ISR or ELHSP', and bycontacts which reflect the position of the adjacent track switch.

For an understanding of the present invention it may be assumed that thetrack switches IW and 3W remain in their normal position, in which casesignal ZRA or 4LA is energized normal or reverse, when its signalcontrol relay is reversed, in accordance with the polarity of thecurrent supplied to its line relay, while signals 2R3 and LB remaindeenergized.

The equipment at the left-hand or west end of the stretch includes a C.T. C. system field station unit designated station l2, and the equipmentat the right-hand or east end of the stretch includes a C. T. C. systemfield station unit designated station 3- 3.

The field stations are connected with the ofiice over a pair of linewires, not shown, by a code communication system which may be of thetype shown in Letters Patent of the United States No. 2,229,249, issuedJanuary 21, 1941, to L. V. Lewis, or in application for Letters Patentof the United States, Serial No. 496,907, filed July 31, 1943, by A. P.Jackel, now Patent No. 2,411,375, granted .Nov. 19, 1946, which systemis described in Manual 596A of the Union Switch and Signal Company,Swissvale, Pa.

Consideration of the detailed mode of operation of the codecommunication system is not needed for an understanding of our inventionand it is deemed sufficient to point out that a field station isprovided at each end of each track stretch to be controlled and thatcoding units are provided at the office and at each field station andare connected by a pair of line wires, not shown, over which controlcodes are transmitted at times from the ofiice to a selected fieldstation, and at other times indication codes are transmitted over thesame line wires from the .diiferent field stations to the office withoutinterference. Transmission of each code includes the temporaryestablishment of a plurality of communication channels, such, forexample, as

seven, between the oifice and a station to position a group of relays.

Each code includes a distinctive code call by means of which a selectorrelay l-ZS' or 3-4S at the ofiice, shown in Fig. 2 and a similar relay,not shown, at one station only is energized to efiect temporaryestablishment of seven communication channels between the office and thestation. The different stations have difierent code calls, consequentlythe selector relays for different stations or panels are not energizedat the same time, and the same channels provide communication atdifferent times with all of the stations.

The explanation of this invention requires only three channels employedin the transmis- I sion of control codes and five channels employed inthe transmission of indication codes, and in order to simplify thedisclosure the other channels and related apparatus have not been shown.

The channels employed in the transmission of control codes aredesignated 2, 5 and I, and the channels employed in the transmission ofindication codes are designated l0, l2, l3, l4 and I5, the numbersemployed to designate these channels being the same as are employed todesignate the corresponding channels in the above-identified applicationof H. S. Young.

It is to be understood that the system of our invention is made up of anumber of unit portions generally similar to the one shown in thedrawings, but as the invention may be fully understood from one suchportion, only one has been illustrated in the drawings.

The office and field stations are each provided with a suitable sourceof direct current, such as a storage battery, not shown, the terminalsof which are designated B and C in the drawings.

In most instances in the drawings the relay contacts are locateddirectly under the Winding of the relay, but in some cases in order tosimplify the drawings, relay contacts are separated from the relaywinding and in these instances the'relay with which the contacts areassociated is designated by appropriate reference characters placedabove the contacts.

The equipment at each field station includes a starting relay FST, whichresponds to a change in position of any of the associated indicatingrelays to provide connection from terminal B of a source of current tothe indication channels to effect delivery of indication codes over theline wires during the time that a delivery relay D at the ofiice isenergized to thereby position a group of indication relays in accordancewith the condition of energization of the indication channels.

The indication relays at the oflice governed from the'field station l2,at the left-hand or west end of the single track stretch, include atrack indication relay ITK which controls a lamp in the track diagram ofthe control machine to indicate the condition of occupancy of thedetector section !T, Fig. 1A, containing the track switch IW, the relayITK being controlled by the track relay ITR for the track section;-

repeats the stop indications of the signals 2RA and ZRB; and a blockindication relay ZRBK controlled by the relay ZRBP which in turn isgoverned by trafiic conditions in the single track stretch.

The relays at the field station 34 at the right-hand end of the singletrack stretch function in a similar manner to control the relays 3TK,4LI-IK and ALBK at the oflice.

The block indication lamp BKE in the track diagram of the controlmachine is governed by the relays ZRBK and 4LBK, one of which indicatesthe condition of occupancy of a portion of the single track stretch andthe other of which indicates the condition of occupancy of the remainderof the single track stretch.

The signal levers ZSIG and 4SIG on the panel of the control machine arethe usual three-position levers for the code control of the signalcontrol relays at the field stations at the op posite ends of thestretch. The signal levers ZSIG and 481G are electrically interlockedwith respect to the control of train movements into the interveningsingle track stretch by electroresponsive means comprising a masterdirectional polarized relay 2-4LP, as in the above identifiedapplication of H. S. Young and also in his Letters Patent of the UnitedStates No. 2,326,991.

Relay 24LP determines the direction for traific movements through thestretch, and is energized whenever a signal lever is reversed with theobject of clearing a signal to authorize a train to enter the stretch,provided the indicated tramc conditions are such as to makeit proper tochange the trailic direction. Under other conditions, relay 2-4LP, islocked deenergized, and it then prevents interference with traffic ifthe operator should attempt to reverse the direction, or to clear anopposing signal.

With relay 24LP in its normal position as shown, if lever 4SIG is movedto position L, lamp WFE is lighted to designate the right to leftdirection, while if lever ZSIG is moved to position R with lever 481G inposition N or R, relay 2-4LP reverses, if the locking conditionspermit,and then lights lamp EFE to designate the left to rightdirection. In either case, the pressing of the starting buttonassociated with the operated lever causes the transmission of a controlcode to the corresponding station 3-4 or |2 to operate the signalcontrol relay for the signal which such lever controls, but only ifrelay 2--4LP occupies the corresponding normal or reverse position.

In the event the position of relay 26LP is changed, as for example, whenrelay 2 iLP is reversed by moving lever ZSIG to position R, the controlcode which reverses the signal control relay also reverses theassociated trafiic relay, and the starting button operation whichinitiates this code causes the transmission of a second control code bywhich the traffic relay at the opposite end of the stretch is restoredto normal, so as to reverse the direction ofenergization of the linecircuit system to enable signal 4RA to be cleared.

The clearing of a signal is indicated by the lighting of lampscontrolled by the corresponding signal indication relay, the operationof whichin response to the clearing ofthe signal locks relay 24LPdeenergized. As the train governed by the signal moves through thestretch its progress is indicated by the lighting of lamps in the trackdiagram by the track and block indication relays as these aresuccessively energized by indication codes initiated by the train. Relay2-4LP is maintained deenergized unt-il lever ZSIG is restored toposition N or L, lever ASIG to position N or R and all of thoseindication relays have been released and indicate that the block isvacant and that the head block signals are at stop.

The relay 2-4LP has associated therewith relays 24LPS and 2- 3BKSR whichare governed in the manner explained in detail in application forLetters Patent of the United States, Serial No. 567,188, filed December8, 1944, by F. T. Pascoe and A. L. Jerome, now Patent No. 2,411,387,granted Nov. 19, 1946. Relay 2-4LPS is av normally energized relay therelease of which indicates that the position of relay 2'(lLP has beenchanged, and its purpose is to operate relays 2-4BKSR, 2RBK and ALBK inresponse to such change. One purpose of relay 2-4BKSR is to store ablock clear indication registered 5 by relays ZRBBZ and 4LBK to enablerelay 2-4LP to be operated in such manner as toprevent he locking ofrelay 25LP by these relays and the lighting of the block occupancyindicator BKE while the wayside system is being reversed and isincapable of indicating traokway conditions, in order to enable theoperator to restore the original trainc direction, if for any reason itsreversal cannot be consumated. Another purpose is to establish circuitsfor the starting relays governing transmission of control codes to thestations at opposite ends of the stretch so as to insure that controlcodes will be transmitted to both stations for the operation of thetrafiic relays, following a change in the position of relay 2-$LP..

The relay 2-4LP also has associated therewith a traffic locking relay2%FL and a releasing relay 2-3FLO, which are provided in accordance withthe present invention in order to control the relay 23LP under certainconditions not provided for by any of the other relays referred to, ashereinafter explained in detail.

The push-buttons l-2STB and 3-4STB are the starting buttons foroperating the usual code starting relays l-2ST and 3-5ST by means ofwhich control code are initiated and the corresponding stationsselected. Each starting relay when energized initiates a control code asdescribed in Lewis Patent No. 2,229,249 including a code call forenergizing a selector relay l-2S or 3-48 for the same panel. Eachselector relay when energized releases the associated starting relay andconnects terminal B of a local source of energy to selected ones of thecontrol channels in accordance with the positions of the signal leversand of contacts of the master directional relay 24LP.

The equipment is arranged so that when energy is applied to channel 2and a control code is transmitted to a field station, the trafiicdirectional relay ZWFSR or :EEFSR at that station is operated tocondition the wayside apparatus to make that end of the stretch an exitor leaving end. Similarly, the equipment is arranged so that when energyis not applied to channel 2 and a control code is transmitted to a fieldstation the traffic direction control relay is operated to co7editionthe wayside apparatus to make that end of the stretch an entrance end sothat the signal at that point may be controlled by the wayside circuitson operation of the associated signal relay.

The equipment is also arranged so that, when energy is supplied-to thecode channel governing a signal control relay, such as, for example,channel 5 or 7, and a control code is transmitted to a field station,the signal control relay at that station, such as relay dLHSR. orZRHSR,v is operated by the code to render the signal'subject to thecontrol of the wayside circuits. When energy is not supplied to the codechannel governing a signal control relay, and a control code istransmitted to a field station, the signal control relay at that stationis restored to normal by the code to keep the signal at stopirrespective of the wayside circuits.

The signal levers ZSIG and 481G are of the three-position type and eachhas a normal center position N, a left-hand position L, and a righthandposition R. The levers control contacts which are shown diagrammaticallyin the'drawings, the contacts which are closed in th'e'lefthand positionof the lever being designated L; those which are closed in theright-hand position of the lever being designated R; those which areclosedin either the normal or the left-hand position of the lever beingdesignated NL; and those which are closed in either the normal or therighthand position of the lever being designated NR.

The equipment at the oifice includes a relay MP which is energized fromterminal 5? of the office coding unit as shown in Manual 506A of TheUnion Switch and Signal Company with the Signal Company with the resultthat relay MP is energized when and only when the ofiice coding unit istransmitting a control code. The offioe equipment also includes a relayMill? which energized from terminal 8 of the coding unit with the resultthat relay M8? is normally energized but is momentarily deenergizedafter the eighth step of each control code.

The equipment is shown in the condition which it assumes when the trackstretch is vacant, the signals 2R, and 4L are at stop, and the signalingapparatus prepares the stretch for westbound traific. At this time thecontacts 29 and 21' of the traific directional relay 2WFSR at thelefthand or west end of the stretch are in their left-hand or normalpositions and connect the line wires 23 and 24 over back contacts 25 and26' of rela ZLAlPC to a source" or energy series with an approach relayZRAR. Relay ZLAPC is controlled as shown and described in theaboveidentified application of H. S. Young, so that it is energized onlywhen signal ZLA is cleared. The energy supplied to the line wires 23 and24 feeds over front contacts of track relays tTR, 2TB, and 4TB, overback contacts 2'! and 28 of relay 5RPC, and back contacts 36 and 3dofrelay 5RSR to the winding of signal 5L and causes this signal, whenlighted, to display its yellow or caution indication. The energysupplied to line wires 23 and 24 through the winding of relay 2RAR keepscontact 33 of the relay" picked up to establish a circuit for relay ZRBPand contact 34 of relay ZRBP is picked up to interrupt the circuitleading to terminal M'of the C. T. C. system field station unit and thuscause indication codes sent to the ofiice to release relay ZRBK.

At this time signals 2RA and 2RB are at stop' so the circuit of relay2RRGP'is complete and its contact 35 interrupts the supply of energy toterminal of the C. T. C. system field station unit, and as section IT isvacant, contact 36 of relay ITR is picked up and interrupts the supplyof energy to terminal 10 of the field station unit.

Accordingly, indication codes sent to the .oflic'e from this stationrelease relays ZRHK and ITK.

As signal 5L is conditioned to display its yellow" indication, energy issupplied over back contact G and front contact Y of the signal to relaySLPC and its contacts are picked up to cause energy of normal polarityto be supplied to line wires 40 and 4| leading to the winding of signal6L. At this time wire 4| is connected to terminal C of a source overfront contact 42 of relay ELPC, and wire 40 is connected over frontcontact 43 of relay LPC, front contact 45 of relay 4TB, winding of relayELAR, and back contacts Y and G of signal 5R to terminal B of thesource. The energy supplied to signal 6L causes it, when lighted, todisplay its green or clear indication, while energy is supplied overback contact Y and front contact G of the signal 6L to relay BLPC withthe result that its contacts are picked up and cause energy of normalpolarity to be supplied to line wires 48 and 49 over a circuit similarto that described above for line wires 48 and 4!. This circuit includesin series therewith the approach relay GLAR.

The energy supplied to line wires 48 and 49 is supplied over contacts 59and 5! of relay lEFSR in their right-hand or reverse position to a polarrelay 4LHD to pick up its neutral contacts and to cause its polarcontacts to occupy their lefthand or normal positions so that polarcontact 53 and neutral contact 54 provide a circuit for relay 4LBP andcontact 56 of relay 4LBP interrupts the supply of energy to terminal l2of the field station unit and causes indication codes sent to the officeto release relay 4LBK.

As shown, the contacts 58 and 59 of the signal control relay 4LHSR arein their left-hand or normal positions and interrupt the circuits forsupplying energy to the windings of signals 4LA and 4LB and thesesignals are both at stop and establish the circuit of relay 4LRGP sothat its contact 60 interrupts the supply of energy to terminal l3 ofthe field station unit. As section 3T is vacant, contact SI of trackrelay 3TB interrupts the supply of energy to terminal l6 of the fieldstation unit, and indication codes sent to the ofiice from this stationrelease relays 4LI-IK and 3TK.

Referring to Fig. 2, which shows the equipment at the office, thecontacts of relay 24LP are in their left-hand or normal position inwhich they designate west-bound tranic in the stretch shown in Figs. 1Aand 1B. In addition, at this time relay 24LPS is energized by currentsupplied over its stick circuit, and relays 24BKSR, 24FL and 24FLO arereleased. As the relay 24FL and the indication relays 4LI-IK, ZRHK,4LBK, 2RBK, 3TK and ITK are all released, energy may be supplied to oneor the other of the windings of the relay 24LP on movement of the signallever ZSIG or 451G to thereby move the contacts of relay 2-4LP if theoperator wishes to change the designated traffic direction.

For purposes of illustration it will be assumed that the operatorwishes'to clear the signal 4LA to authorize a westbound train to enterthe stretch. In order to clear this signal, he moves lever 4SIG to itsleft-hand position L and presses the starting button 34STB to pick upthe starting relay 3-4ST and cause a control code to be sent to fieldstation 34. On this movement of the lever 4SIG, the circuit is completedto supply energy to the lower winding of relay 2-4LP, but as itscontacts are already in their left-hand position, the supply of energyto this winding is without effect.

During transmission of the initial or station selection steps of thecontrol code sent to station 34, the selector relay 34S at the office ispicked up with the result that energy is supplied over normal polarcontact it! of relay 24LP, front contact 7! of relay 34S, back contact12 of relay 2-4FLO, and a contact of lever 4SIG to terminal 5 of theoffice coding unit during transmission of the function steps of thecontrol code sent to station 34, and the control code sent to station 34reverses the contacts of relav 4LI-ISR.

In addition, during operation of the oiilce coding unit to transmit acontrol code, energy is supplied to terminal 51 and picks up relay MP sothat on picking up of relay 34S energy is supplied over front contact'55 of relay MP, contacts l6 and H of relay 24FL, normal polar contact18 of relay 24LP, front contact of relay 34S, a contact of lever 4SIG,back contact 8! of relay 4LI-IK, back contact 82 of relay 3TK, and backcontacts 83 of relay 34D and 84 of relay 2--4FLO in multiple to thelower winding of relay 24FL. The energy supplied to this winding picksup the relay contacts so that contact 85 moves contact 11 out ofengagement with contact 76 and connects terminal B of the battery tocontact H to provide a stick circuit for relay 24FL and keep itscontacts picked up after release of relay MP. In addition, When relay2-4FL picks up, it contact 88 shunts contact 80 of relay 34S and thecontact of lever 4SIG in the pick-up circuit of relay Z4FL and thuskeeps relay 2--4FL picked up after release of relay 34S or after lever481G is moved from its position L.

When relay 24FL picks up, its contact 81 interrupts the circuits ofrelay 24LP to thereby prevent supply of energy to the windings of thisrelay and thus prevent movement of the relay contacts to change thedesignated direction of traffic in the track stretch controlled thereby.

As relay 24FL is picked up as soon as relay 345 picks up, which occursduring the station selection steps and prior to the function steps ofthe control code, and as relay 24FL when picked up locks relay 24LP toprevent a change in the designated traific direction, there is nopossibility that the contacts of relay 24LP can be moved to change thedesignated trafiic direction aftera control code has been sent to cleara signal. If, for example, after the control code is sent to station 34to clear the signal 4LA but prior to receipt at the office of the signalclear indication code to pick up relay 4LI-IK, the operator moves lever4SIG to its center or its righthand position, and also moves lever 2SIGto its right-hand position, energy will not be supplied to the upperwinding of relay 24LP since contact 8'! of relay 24FL is picked up andinterrupts the circuits of relay 2-4LP. Accordingly, the contacts ofrelay 24LP are certain to remain in their existing positions andmaintain the direction of trafiic which was designated at the time thesignal control code was transmitted, in this case, westbound trafiic.

If under the conditions outlined above the contacts of relay 24LP shouldbe moved and a control code should thereafter be sent to station l2 tocondition that end of the stretch to be an entrance end, it would causethe wayside equipment to attempt to establish eastbound trafiic andwould result in putting to stop the westbound wayside signals withresultant interference with movement of westbound trafiic in the 1 lstretch which had been authorized by clearing of signal ALA.

Since relay 2-4FL, which is being added by this invention, operates tolock the relay 2-4LP as soon as the signal clearing control code issent, there is no possibility that subsequent movement of the signalcontrol levers will cause movement of the contacts of relay 24LP withresultant interference with the designated trafiic direction.

As explained above, when the signal control code is received at fieldstation 3--4, the contacts 58 and 59 of relay ALI-18R. are reversed tocause energy to be supplied to the Winding of signal iLA over thecircuit controlled by neutral and polar contacts of relay iLI-ID and bycontacts 90 and 91 which are governed in accordance with the position ofswitch 3W so as to establish the circuit of signal ALA when and onlywhen the switch i in its normal position As shown, the switch 3W is inits normal position and the polar contacts of relay iLHD are in theirnormal position so that energy is supplied to the winding of signal @LAto cause itto display its green or clear indication. When signal QLAclears, the circuit of relay ALRGP is interrupted and it releases tocause energy to be supplied over its back contact til to terminal $3 ofthe field station unit while a contact of relay GLRGP momentarilyinterrupts the circuit oi the starting relay 34 FST to cause anindication code to be sent to the office to pick up relay iL-HK to showthat signal #Lif has cleared.

In addition, when relay ALRGP releases, its contact 115 interrupts thecircuit of an approach locking stick relay yiLAS and it releases tointerrupt its own stick circuit, while contact H6 of the relay flLASestablishes a circuit to supply energy tcterrninal i3 of the fieldstation unit when contact 59 of relay GLHSR is in its normal position.The relay lLAS, when released, operates in the well-known manner toprevent movement of the switch 3W and to prevent clearing of the signalARA or 413B, while the relay ALAS may operate as explained in theabove-identified application of H. S. Young to control the supply ofenergyto the terminal, not shown, of the field station unit whichcontrols the indications of signals {ERA and QRB to thereby send to theoflice a distinctive indication when the time looking isin effect.

When relay ALHK picks up, it establishes a stick circuit for itselfwhile its contact 8! interrupts the stick circuit for relay 24FL and itscontacts release, but before contact 8'? of relay 1 2 sFL establishesthe circuit of relay 24LP, contact of relay 4LHK is picked up tointerrupt this circuit and thereby prevent movement of the contacts ofrelay 2 lLP while a signal governing entrance of traffic into thestretch is displaying a permissive indication.

Under some conditions transmission of indication codes from the fieldstation to the office may be delayed and a train may accept signal 4LAand enter the single track stretch before the signal clear indicationcode is sent to the oifice. When a westbound train enters section 3T,the track relay ST-R. releases to interrupt the circuit of the slowrelease repeater relay 3'1? and cause energy to be supplied over backcontact 94 of relay 3TH and front contact 95 of relay STP to the lowerwinding of relay QLHSR during the release period of relay STP andcontacts 58 and 5%} of relay @LHSR are moved to their normal position tointerrupt the supply of energy to the w nding of s na s jAa this caus ti n to display its stop indication. Also on release of relay itscontacts 96 and 97 interrupt the circuit of relay 4LHD and its neutralcontacts release to additionally interrupt the circuit of signal Whensignal the displays its stop indication, the circuit of relay (A LRGP iscomplete and its contact 68 interrupts one branch of the circuit leadingto terminal 13 of the C. T. C. unit.

When relay iLRGP picks up, energy is supplied over its front contact H5and a back contact of relay 3TR to relay 4LAS and its contacts pick upto establish a stick circuit to keep the relay energized after relay3TB, picks up, while contact H6 of relay ILAS interrupts the secondbranch of the circuit leading to terminal 13 of the C. 'I'. C. fieldstation unit, consequently indication codes which follow a control codefor clearing signal 4LA do not pick up relay .(lLHK unless transmittedbefore the train governed by the signal enters section 31.

However, when relay 3TH is released, its contact 5] establishes thecircuit for supplyingenergy to terminal in of the field station unit sothat indication codes sent to the ofiice pick up relay 3TK. The supplyof energy to terminal 10 of the field station unit may be controlled bytrack relay STR through a stick repeater relay, not shown,

,. which operates as explained in the above-mentioned Manual 506A tomaintain the supply of energy to terminal Ii) until an indication codehas been sent to the office. This insures that the indication ofoccupancy of section 3T will be sent to the ofiice even throughtransmission of the indication code is delayed so that section 3T isvacated before the indication is transmitted.

When the relay SIK at the ofiice picks up, its contact $8 interrupts thecircuit of relay 2-4LP, and its contact 82 interrupts the stick circuitfor relay 2-4FL and its contacts release. As contact 98 of relay 3TKinterrupts the circuit of relay 2,4LP before contact 81 of relay 2 4FLreleases, there is no period during which the cir- 1 cuit of relay 2-4LPis established, and therefore no possibility that energy may be suppliedto relay 2-4LP to move its contacts and change the designated traificdirection during occupancy of the stretch.

From the foregoing it will be seen that inclusion of a contact of theindication relay STK for the detector section at the entrance end of thestretch in the control of relay 2-4FL insures that this'relay will bereleased upon entrance of a train into the stretch if the relay has notal read been released by receipt of a signal clear indication, andthereby makes certain that the locking of relay 24LP will be releasedwhen the stretch is vacated.

On release of relay lLHD at field station 34 its neutral contact "5 1interrupts the circuit of relay ZLBP and contact 55 of relay 4LBPreleases to supply energ to terminal I2 01" the field station unit andcause indication codes sent to the office to pickup relay Z-LBK andcause its contact 93 to interrupt the circuit of relay 2- lLP.

On continued movement of the train through the stretch, the block anddetector section indication relays control the circuits of the detectorsection and block occupancy lamps in the track mode1 on the panel of thecontrol machine, while contacts of these relays interrupt the circuitsof relay 24LP to insure that the contacts of this relay remain in theirleft-hand position and maintain westbound traific. As hereinafterexplained,

the circuits of the traffic direction lamps and EFE are controlled in aSomewhat different manner than heretofore.

If desired, the contact 8! of relay 4LI-1K in the pick-up and stickcircuits of relay 2--4FL may be omitted, and if this is done, the relay24FL when picked up remains picked up until released by the relay BTK,or is released in the manner explained below.

If an indication code is sent to the ofiice after a signal clear controlcode has been transmitted but before the signal has cleared or a trainhas entered the stretch, contact 83 of relay 34D will pick upmomentarily, but at such times this contact is shunted by contact 84 ofrelay 2-4F'LO so the stick circuit of relay 24FL is not interrupted andrelay 2-4FL remains picked up tointerrupt the circuit of relay 2-4LP.

After a control code has been transmitted to clear a signal governingentrance of trains into one end of the stretch and before an indicationcode has been received in response thereto, the operator may find itadvantageous to change the direction of traffic in the stretch and clearthe signal governing entrance of trafilc into the stretch at the otherend. This equipment is arranged so that after a, signal clear code hasbeen transmitted, the operator can regain control of of the trafficdirection designating relay to change the direction of traffic in thestretch only after it has been determined that it is safe for him to doso.

As explained above, when a control code is sent to clear signal 4LA, therelay 24FL is picked up to interrupt the circuits of the relay 2-4LP andthus prevent a change in the designated traffic direction. If theoperator now decides to establish eastbound traiiic in the stretch andto clear signal ZRA, he must first move signal lever ASIG to its normalposition or to its right-hand position and send a control code to fieldstation 3-4. On this movement of the lever 4SIG the contact in thecircuit leading to terminal 5 of the office coding unit is opened tocause the controlcode sent to stations 3-4 to move the contacts of relaylLHSR to their normal positions and thus cause signal iLA to display itsstop indication.

When lever 4SIG is in its center or its righthand position, but relay2-4FL is picked up because a signal clear control code has beentransmitted and has not been followed by an indication code which willrelease the relay 24FL, and a control code is sent to station 34,terminal B of the battery is connected to one terminal of the winding ofrelay 24FLO over the circuit which includes contacts 85 and ll of relay2-4FL, normal polar contact 18 of relay 2LP, front contact 80 of relay34S which is picked up during transmission of a control code to station34, contact NR of lever 481G, contacts WI and 102 of relay 24FLO, andfront contact I03 of relay 24FL.-

As explained in Manual 506A referred to above, the supply of energy torelay M8P is temporarily interrupted during the eighth step of thecontrol code sent to station 3-4 and the contacts of relay MBP releasefor a short time interval. When relay M8P releases, terminal C of thesource is connected over back contact 105 of relay MBP, and contacts I06and I0! of relay 2-4FLO 1 to a terminal of the winding of relay 24FLO tocomplete the circuit of the relay. The contacts of relay 24FLO now pickup and contact I08 moves contact I02 out of engagement with contact IOIand connects terminal B of the source over front contact 103 of relay2--4FL to one:

terminal of the winding of relay 24FLO, and contact I09 moves contactI01 out of engagement with contact I06 and connects terminal C ofthesource to the other terminal of the relay winding so that, afterpicking up of relay M8P, relay 2 lFLO is maintained energized by currentsupplied over a stick circuit governed by contact [03 of relay 24FL.When relay 2-4FLO picks up, its contact 84 in the circuit of relay,2.4FL is opened, but energy continues to be supplied to relay 2-4FL overback contact 83 of relay 3-4D so relay 2'4FL remains picked up and itscontact 8! interrupts the circuits of relay 2-4LP. Also when relay2-4FLO picks up, its contact 12 interrupts the circuit leading toterminal 5 of the oflice coding unit to thereby prevent supply of.

energy to this terminal in the event the lever 4SIG is restored to itsleft-hand position after picking up of relay 2 iFLO but prior totransmission of the step of the control code governed by terminal 5 ofthe ofiice coding unit. Opening of contact 12 of relay 2-4FLO,therefore, guarantees that the signal control element of the controlcode sent to station 34 will cause' the contacts of relay dLHSR to bemoved to their normal positions to cause signal 4LA to displayits stopindication. As signal 4LA displays its stop indication the circuit ofrelay 4LRGP is complete and it picks up to interrupt the. branch of thecircuit which it controls leading to terminal l3.

of field station 3-4.

The signal stop control code sent to station 3-4 causes this station totransmit an indica- A tion code to the office and when this code is re-'ceived at the oiilce the delivery relay 34D picks up with the resultthat its contact 83 in the cir-j cuit of relay 24FL is opened. Ascontact 84 of relay 24FLO is also open, the supply of energy.

to the lower winding of relay 2-4FL over the stick circuit for thiswinding is interrupted and the relay contacts release to additionallyinterrupt the relay stick circuit, while contact I03 of relay 2-4F'Linterrupts the circuit of relay 2-4FLO and it releases.

After release of relay 2-4-FL as a result of re- 1 at this time mayresult in picking up of one ormore of the relays 4LHK, 4LBK or STK tointerrupt the circuits of relay 2-4LP and thus main-' tain theestablished direction of traflic in the" single track stretch.

If the signal clea control code previously sent to station 34 resultedin clearing of signal 4LA with consequent release of relay ALRGP, itscontact H5 will interrupt the circuit of relay GLASY and it releases tointerrupt its own stick cir-' cuit, and contact N6 of relay 4LASestablishes a connection to terminal l3 of the field station unitprovided contact 59 of relay iLHSR. is in its" stop as a result ofpassage of a train, the relay ALRGP picks up but relay 4LAS'remainsreleased so that energy is supplied to the time element device 4TER.After a substantial time interval,

l 5 such "as .6 minutes, the contacts of the device ATER pick up andenergy is supplied over its contact -Iil8 torelayALAS to pick up itscontacts to interrupt thecircuitof device 4TER and establish a stickcircuit for relay lLAS.

When contact vHi5 of relay QLAS is released andcontactfiil of relayALHSR is in its normal position, the battery is connectedto'terminal 43of the-field station unit to cause indication codes sent to the officeto pick up relayALI-IK even though signal LA isat stop and relay ALRGPis picked up.

Innthis case, as explained in the-above-identified application of H. S.Young, another indication relay ARHK is picked up along with relay 4LHK,which prevents the display of a clearsignal indication by relay 4LHK andprovides a distinctive indication of the operation of the device 4TER.

*If signal 'ALA .had .been clearedby the signal clear control code andhad been accepted by a train, the signal would have been put-to stop byrelease of relay .3TR, thereby picking up relay QLRGP, while on picking:up of relay iLRGP a pick-up circuit including its front contact H5 isestablished for relay ALAS and it picks up to establish a stick circuitfor itself and to interrupt the supply of energy to terminal l3 of thefield station unit with the result the indication codes subsequentlysent to the office do not pick up relay 4LI-IK.

If signal dLA had been put to stop by entrance of a train into thestretch, the relay 3TB will-be released so that its .contact 6!establishes connection to terminal [0 of the field station unit to causeindication codes sent to the ofiice to pick up relay 3TK. Also, if atrain enters the stretch, the neutral contacts of relay ALI-ID arereleased and interrupt the circuit of relay 4LBP so itscontact 56establishes the circuit to'supply energ to terminal i2 of the fieldstation unit-so that indication codes sent to the office pick up relaydL-BK.

If for any reason the signal ALA did not clear in response to thesignalclear control code sent to station .3-4, the relays lLRGP and ALASremain energized and in this case a train would not have entered thestretch and relays 3TB, 4LHD and GLBP would'have remained energized andindication codes sent to the oiiice would not pick up relay iLBK,4LI-IKor 3TK.

It will be seen that after the signal stop code has been received at thefield station the indication codes thereafter sent to the ofi'lce showconditions at the field station. If-the signal GLA- had been clearedbythe signal clear control code a and was put to stop by the signal stopcode so that the time locking is effective, the indication code sent tothe oflice will pick :up relay ILHK so that its contact '92 interruptsthe circuits of relay 2-4LP and thus prevents a change in the designatedtraffic direction 'until the time interval determined by device l'I ERexpires, at which time relay ALAS picks up and an indication code issent to the ofiice to release relay 4LHK. This is proper since thesignal ALA, when clear, may have caused a west-bound train to advancetoward the signal to enter the single track stretch, and, after thesignal is put manually to stop, this train may be unable to stop beforepassing the signal. If a train should overrun the signal and enter thesingle track stretch, it would release relays 3TB, iLE-ID and 4LBP tocause indication codes to be sent to the ofiice to pick up relays ETKand ALBK and inter- 16 rupt the circuits of relay 2-4LP and thus prevent a change in the designated traffic direction.

Similarly, if a train had passed signal 4LA and had entered the singletrack stretch before the signal stop control code was received atstation 3-4, the indication codes subsequently sent to the oilice wouldpick up relaysdLBK and STK to prevent movement of the contacts of relay2-4LP and thus maintain the established direction of trafiic.

If the signal clear control code sent to station 3-4 had not resulted inclearing of the signal, and if no train has entered the stretch, theindication code sent to the office following the signal stop controlcode will not pick up either of the relays dLBK, dLHK or 3TK, and asrelay 2-4FL is released, the circuits of relay 2--tLP are complete andthe operator is free to move its contacts and change the direction oftraffic in the single track stretch.

From the foregoing it will be seen that relay 2-4FL operates to lock thetraffic direction designating relay 24LP and thus maintain theestablished traific direction as soon as a control code to clear asignal is transmitted. This eliminates the possibility of interferencewith trafiic in a stretch in the interval between transmission of asignal clear control code and receipt of an indication code showing thatthe signal has cleared or has been accepted by a train.

It will also be seen that after a signal clear control code has beentransmitted the operator can regain control of relay 2-4LP by firsttransmitting a signal stop control code and thereafter receiving anindication code to show whether it is proper to permit the establishedtrafiic direction to be disturbed.

If the operator desires to change the direction of trafiic in the singletrack stretch from westbound to eastbound, he may do so providing thestretch is unoccupied and the signals governing entrance of traffic intothe stretch are at stop. Under these conditions the relays controllingthe circuits of the windings of relay 24LP are released and if leverdSIG is in its center or its right-hand position, and lever ZSIG ismoved to its right-hand position, energy is supplied to the upperwinding of relay Z-GLP and its contacts are moved to their right-hand orreverse position. The change inthe position of the contacts of relay24LP reverses the polarity of the current supplied to relay 2-LPS,causing this relay to release to open its stick circuit and to closeback contacts over which relays 2-6BKSR, ZRBK and ALBK pick up asexplained in the above-mentioned application Serial No. 567,188 of F. T.Pascoe and A. L. Jerome. If the starting button l-2STB is now pressed,energy is supplied to relays I--2ST and 34ST and they pick up to causecontrol codes to be sent to field stations !-2 and 34. Relay 24,LPSpicks up over the connection now established to terminal 51 of theofiice coding unit, which as already explained is supplied with energyduring the transmission of a control code. At this time contact 10 ofrelay 2-4LP is in 'its right-hand position so that energy is supplied toterminal 2 of the oflice coding unit during the picked-up period ofselector relay 3--4S but'not during the picked-up period of selectorrelay l2S. Accordingly, the control code sent to the field station 34 atthe east end of the stretch moves the contacts of relay 4EFSR to theirnormal po sitions to disconnect line wires t8 and 49 from relay 4LHD andconnect them to a source of energy in series with relay dLAR, therebychanging the east end of the stretch from an entrance to an exit end.Similarly, the control code sent to field station l'2 at the west end ofthe stretch moves the contacts of relay ZWFSR, to their reverse positionto disconnect line wires 23 and 24 from the source of energy and connectthem to relay 2RHD and thus convert the west end of the stretch from anexit to an entrance end.

Referring to Fig. 2, as contact 70 of relay 24LP is in its right-handposition, and assuming lever ZSIG is in its right-hand position, energyis supplied to terminal 7 of the office coding unit during the picked-upperiod of relay |2S and the control code sent to field station l-Zreverses the contacts of relay ZRHSR to cause signal 2RA or ZRB to clearwhen the neu- 1 east end of the stretch to clear signal BR and thus pickup rela GRPC to supply energy to line wires and 4| to clear signal 5Band pick up relay ERPC to supply energy to line wires 23 and 24 toenergize relay ZRHD and cause one or the other of the signals ZRA or ZRBto display a permissive indication. I

Referring again to Fig. 2 it will be seen that when the signal clearcontrol code is sent to station l'2, energy is supplied to the upperwinding of relay 2-4FL over the circuit including front contact 15 ofrelay MP, contacts 15 and ll of relay 2-4FL, reverse polar contact 78 ofrelay 24LP, front contact H2 of relay l-2S, contact R of lever ZSIG,back contact H3 of relay ZRHK, back contact H4 of relay ITK, and backcontact H5 of relay I2D and back contact H6 of relay 24FLO in parallel.When relay 24FL picks up, its contacts 85 and Ti provide a stick circuitfor the relay, while its contact I213 establishes a path shunting thecontact H2 of relay !-2S and the contactR of lever ZSIG. As relay 2-4FLis picked up, its contact 8'! interrupts the circuits of relay 2-4LP toinsure that eastbound trafiic will be maintained until, as explainedabove in connection with westbound trafiic, it is certain that it isproper to change the direction of trafiic in the stretch. The operationof the equipment following transmission of a control code to clear asignal 2R is similar to its operation following transmission of acontrol code to clear a signal 4L and a detailed operation of theequipment at such times is unnecessary.

The trafiic direction indication lamps WFE and EFE are governed bycontact I25 of relay 2-4LP so that one or the other of these lamps maybe lighted depending on the position of contact I25. The circuits of thelamps WFE and EFE are also controlled by the signal levers and by theindication relays so as to be lighted when and onl when it is desirablefor the operator to know the direction of trafiic established or to beestablished in the stretch with which the lamps are associated.

When, for example, neither of the levers ZSIG and ASIG is in a positionto clear a signal governing entrance of trafiic into the stretch,neither of the signals 2R and AL is displaying a permissive indication,the relay 2--4FL is released showing that no control code has beentransmitted to clear signal 4L or 2R, and when, in addition, the entirestretch is unoccupied, there is no reason for the lamp WFE or EFE to belighted and having these lamps dark at such times makes the otherindication lamps on the control panel more effective since the operatorcan devote his entire attention to the lamps, lighting of which has somesignificance.

As soon as a signal lever is moved to a position to clear a signalleading into the stretch it is desirable to indicate to the operator thedirection of trafiic in the stretch, and to thereafter maintain thisindication until conditions I are such that the indication is no longerrequired. The circuit of lamp WFE or EFE- is established as soon as asignal lever is moved to a signal clearing position, is maintained byrelay 24FL after a signal clearing control code is transmitted, and isthereafter maintained by the signal clear indication relay or by theindication relays governed by occupancy of the stretch. When the stretchis vacated and neither of the signal levers is in a position to clear asignal leading into the stretch, the circuit of lamps WFE and EFE isinterrupted and these lamps are extinguished.

A back contact of relay 24BKSR is included in the circuits governed bythe block indication relays ALBK and 2RBK for supplying energy to thelamps WFE and EFE. As explained in our application Serial No. 567,188,the relay 2-4- BKSR, and the relays 2RBK and ALBK are picked up on achange in the position of the contacts of relay 24LP and relay 2--4BKSR,remains picked up until relays 2RBK and lLBK are released by indicationcodes transmitted from the field stations showing that trafiic has beenestablished in the new direction, or until one of the detector sectionindication relays ITK or 3TK is picked up to show that a train hasentered the stretch. Inclusion of the back contact of relay 2--4BKSR in.the circuits governed by relays QRBK and 4LBK for lighting the lampsWFn. and EFE prevents lighting of these lamps by energy supplied overthe contacts of relays ZRBK and 4LBK at times when these relays arepicked up incident to movement of the contacts of relay 24LP and notbecause of occupancy of the stretch. At such times one of these lampsmay. be lighted by energy supplied over another circuit, as, forexample, over a contact of lever 2SIG or 4SIG or over the front contactof relay 24FL. However, the lamps WFE and EFE will not be lighted if nosuch other circuit is established following a movement of the contactsof relay 2-4LP, as might be the case if lever .2SIG is moved to itsposition R or lever 481G is moved to its position L, thereby producingmovement of the contacts of relay 2--4LP, and if the lever is thereaftermoved from this position before a control code is sent.

In the machine circuits shown in Fig. 2 of the drawings a special relay2-4FLO is provided to release relay 24FL upon receipt of an indicationcode from a field station subsequent to transmission of a signal stopcontrol code to that station. It is possible to employ the signalindication relays for this purpose, thereby eliminating the need for therelay 2-4FLO, and Fig. 3 is a fragmentary diagram showing thismodification. The equipment is shown in the condition which it assumeswhen relay 2--4LP designates westbound trafiic, the signals 4L are atstop, and a signal clear control code has not been transmitted so thatrelay 24FL is released,

If the operator wishes to clear signal 4LA, he moves lever 4SIG to theleft and presses the starting button for station 3-4 to cause a controlcode to be sent to that station. When selector relay 34S picks up,energy is supplied to the lower winding of relay 24FL over a circuitidentical with that traced in detail in connection with Fig. 2 exceptthat contact 83A of relay ALI-1K is substituted for contact 83 of relay24FLO. As explained in connection with Fig. 2, when relay 2-4FL picksup, it establishes a stick circuit for itself and a contact of relay24FL interrupts the circuits of relay 2-flLP to insure that the contactsof relay 2- 3LP remain in their left-hand positions and maintainwestbound traiiic in the stretch. The stick circuit for relay 2-4FLestablished at this time includes its own front contact 88 and differsfrom the stick circuit shown in Fig. 2 in that contact 88 shunts thecontact iii of relay QLHK in the relay pick-up circuit as well ascontact 88 of relay 3- 38 and contact L of lever 4SIG.

When relay Z-AFL picks up, its contact I25 establishes the circuitincluding back contact [2? of relay iLl-IK, front contact ll of relay3-451, and contact L of lever GSIG for supplying energy to terminal 5 ofthe ofiice coding unit to cause the control code sent to station 35 toinclude a signal clearing element. If a signal clear control code issent while relay ELHK is picked up and relay 2-4FL is released, therelay 2-4FL remains released as its pick-up circuit is interrupted bycontact 8! of relay ALHK, and, as relay 24FL remains released, itscontact i3l maintains the circuit of lamp ALE and it remains g,-

lightedand contact i26 of relay 2-4FL and contact I27 of relay iLHK'establish the circuit to terminal 5 of the ofiice coding unit.

When signal 4LA clears in response to the control code, an indicationcode is sent to the office to pick up relay lLHK. At the time thisinclication code is registered at the oihce the delivery relay 34D picksup with the result that its contact 8 1 in the stick circuit of relay24FLis open, and when relay ALHK picks up so that its contact 83A in thestick circuit of relay 2-4FL is also open, the stick circuit for relay2- iF-L is interrupted and the relay contacts release to additionallyinterrupt the relay stick'circuit. The relay 34D is picked up for only ashort time, but this period is long enough to insure release of relay24FL, while on release of reiay 34D the relay ALI-1K is maintainedpicked up by a stick circuit in the usual manner.

When relay GLHK picks up, a contact of the relay interrupts the circuitsof relay 2- 413? to insure that it maintains the established trailicdirection, and relay QLHK is picked up and relay 2-4FL is released,energy is supplied over front contact l3i3 of relay 4LHK and backcontact iii! of relay 2- iFL to lamp LE above lever 4S IG 'and'this lampis lighted to indicate to the operator that signal tLis displaying apermissive indication. Also on :pickihg'up of relay 4LH-K and' releaseof relay 2'4FL the circuit leading to terminal 5 of the ofiice codingunit is maintained so that as long as lever ASIG remains in its positionL control codes transmitted to station 3 4 will include a signal clearelement and will maintain the display of a permissive indication by oneof the signals 4L;

If a westbound train accepts signal 512A and enters the stretch so thatsignal 411A isput to stop, an indication code will be sent to the officeto release relay ALHK, but to also pick up other indication relays,asfexplaihedin connection with Fig. 2 and thus lock relay 2'4LP.Oil-release of relay iLI-IK its contact ten-interrupt the cir-' cuit oflamp ALE, "it's contacts :8] and 83A establish the pick-up circuit forrelay 2-'' il 1i, andits contact I2? interrupts the 'circuit leading toterminal -5 of the office coding unit to prevent transmission of signalclear control codes unless relay 2-4FL is picked up. On continuedmovement of the train through the stretch, the equipment operatessubstantially as explained in connection with Fig. 2.

The modification shown in Fig. 3 is arranged so that, after a signalclear control code has been transmitted to a field station, the operatorcan regain control of relay 24LP by first sending a signal stop controlcode to the station and thereafter receiving an indication code showingthat conditions are proper to permit him to have control of relay2--4LP.

As explained above, when the signal clear control code is sent tostation 34, the relay 2-4FL is picked up and establishes a stick circuitfor itself. If the operator now decides to I convert the stretch fromwestbound to eastbound traffic, he moves lever LiSIG to its normal or toits right-hand position and presses the starting button 34STB to cause acontrol code to be sent to station 3- As explained in connection withFig, 2, the relay MBP releases momentarily on the eighth step of thecontrol code sent to station 34, at which time contact of relay 34S ispicked up. Accordingly, when relay MHP releases, energy i supplied tothe upper winding of relay cLHK over a circuit, a portion of which iscommon to the stick circuit for the lower winding of relay 2-4FL. Thecircuit for supplying energy to rela ALHK includes contacts 85 and H ofrelay 24FL, contact 18 of relay 24LP, contact 80 of relay 34S, contactNR of lever llSIG, winding of relay lLHK, front contact 03 of relay2-4FL, and back contact N5 of relay M8P. The energy supplied to relayiLI-IK picks up the relay contacts with the result that contact I32 ofrelay 4LHK establishes the relay stick circuit which includes backcontact I33 of relay -3-tD and front contact I34 of relay 24FL inmultiple.

On pickingv up of relay iLHK its contact 8| is opened but is bridged bycontact 88 of relay 24FL,and contact 83A of relay ALHK is opened but isbridged by contact 84* of relay 3-4D since operation of the officecoding unit is such that relay 3-4D is certain to be released at thetime relay ALHK is picked up by energy supplied to its upper windingover the circuit governed by relay M8P. Accordingly, on picking up ofrelay iLHK at this time the stick circuit for relay 2-4FL is maintainedand relay 2-AFL remains picked up. As relays 2-4FL and HLHK are bothpicked up their contacts 26 and i2? interrupt the circuit leading toterminal 5 of the office coding unit to insure that the control codesent to station 34 includes the signal stop element even if lever ASIGshould be moved to its position L.

As relay 24FL is picked up its contact 13! interrupts the circuit oflamp ALE to prevent lighting of this lamp even though relay tLHK ispicked up. This is proper since picking up of relay GLHK at this time isnot the result of a signal clear indication code received from thefield.

As relays 2-4FL and lLHK are both picked up, the circuits of relay 2-4LPare interrupted.

211 as will be clear from Fig. 2, and the relay 24LP is certain tomaintain westbound traific in the stretch.

The control code sent to station 3-4 causes that station to send anindication code to the office, and, when this indication code isregistered at the ofiice, relay 34D picks up with the result that itscontact 84 interrupts the stick circuit for relay 24FL and relay 24FLreleases. When relay 3-4D picks up, its contact I33 interrupts thestickcircuit for relay 4LHK 1 and connects relay lLI-IK to terminal l3 of theofiice coding unit. If at this time energy is not supplied to terminall3, the relay 4LHK will be held picked up by energy supplied over frontcontact I34 of relay 24FL until relay 24FL releases, whereupon relay4LI-IK releases. The stick circuit for relay 4LHK provided by frontcontact I34 of relay 2,4FL insures that relay 'ALHK will remain pickedup and interrupt the stick circuit for relay 2-4FL-until this circuit isinterrupted by release of relay 2-4FL and thereby makes release of relay24FL certain at these times.

If at the time the indication code is'received energy is supplied toterminal [3, as may be the case when the time looking is in efiect, therelay lLHK will remain picked up after release .of relay 2-4FL. If atthe time the indication code is received a train has entered thestretch, the detector section and block indication relays 3TK and 4LBKwill be picked up, as explained in connection with Fig. 2.

In any event the indication code received following the signal stopcontrol code will release 5 relay 2-4FL and establish the circuits ofrelay 24LP unlessthese circuits are interrupted by one-or moreof theother indication relays.

As pointed out above, when a signal stop control code is transmittedfollowing a signal clear control code but prior to receipt of the signalclear indication, the relay 24FL remains picked ,up and the'relay lLHKbecomes picked up with .the result that the lamp 411E is not lighted. If

the signal clear indication is received from the field, the relay ALHKwill be picked up and the when relay 2--4LP designates eastbound trafficin the stretch and a control code is transmitted to. clear one of thesignals 2H. and a detailed explanation of the operation of the equipmentat such times is unnecessary.

Although we have herein illustrated and described two forms of railwaytraflic controlling apparatus embodying our invention, it is understoodthat various. changes and modifications may be made therein within thescope of the appended claims without departing from the spirit and scopeof our invention.

Having thus described our invention, what we claim is:

1. In direction selecting means for a stretch of railway track equippedwith a signaling system governed jointly by traffic direction relays atopposite ends of the stretch so that at times the stretch is conditionedfor traffic movements in 22 one direction and at other times for traificmove= ments in the opposite direction and having a signal at each endfor governing traffic movements into the stretch and a signal controlrelay for each signal for manually governing the clearing thereof inaccordance with the condition of said signaling system, together with acode type remote control system for transmitting control codes forcontrolling the signal control and traffic direction relays from acentral oflice and for transmitting indication codes for indicatingtraflic conditions at said ofiice, in combination, electroresponsivemeans at said o ifice for desi nating the direction for trafiicmovements and for controlling the transmission of codes by saidremotecontrol system by which said trafiic direction relays are operatedto establish the'corresponding direction for traffic movements in saidstretch, an auxiliary relay at the ofiice, means for operating'saidauxiliary relay in response to the transmission of a control code forclearing a signal by operation of its signal control relay, anindication relay at said office for each of said signals, each signalindication relay being operated when an indication is received that theassociated signal is clear and being re stored to its normal positionwhen an indication is received that the associated signal is at stop,

means responsive to the operation of a signal indication relay by anindication code transmitted when a signal is clear for restoring saidauxiliary relay to its normal position, and looking means at said officecomprising normally closed contacts of said auxiliary relay and saidindication relays in a circuit for controlling said electroresponsivemeans, the opening of such contacts being efiective to maintain thedesignated trafiic direction by preventing the energization of saidelectroresponsive means when said auxiliary relay occupies its operatedposition or either of said signal indication relays is in its operatedposition.

2. In direction selecting means for a stretch of railway track equippedwith a signaling system governed jointly by traffic direction relays atopposite ends of the stretch so that at times the stretch is conditionedfor traliic movements in one direction and at other times for trafficmovements in the opposite direction and having a signal at each end forgoverning trafiic movements into the stretch and a signal control relayfor each signal for manually governing the clearing thereof inaccordance with the condition of said signaling system, together with acode type remote control system for transmitting control codes forcontrolling the signal control and traffic direction relays from acentral office and for transmitting indication codes for indicatintraffic conditions at said office, in combination, electroresponsivemeans at said oflice 'for designating the direction for traflicmovements and for controlling the transmission of codes by said remotecontrol system by which said trafnc direction relays are operated toestablish the correspondingdirection for trafiic movements in saidstretch, an auxiliary relay at the ofiice, means foroperating saidauxiliary relay in response to the transmission of a control indicationis received that the associated signal is at stop, means forrestoring-said auxiliary relay to its normal position in response to theoperation of a signal indication relay by an indication code transmittedwhen a signal is clear, occupancy indication means at said ofiice whichis operated when an indication is received that said stretch is occupiedand is restored to its normal position when an indication is receivedthat said stretch is unoccupied, and locking means at said controloifice comprising normally closed contacts controlled by said auxiliaryrelay, said signal indication relays and said occupancy indication meansin a circuit -for controlling said electroresponsive means, the openingof such contacts being effective to maintain the designated trafiicdirection by preventing the energization of said electroresponsive meanswhen said auxiliary relay, said occupancy indication means, or either ofsaid signal indication relays occupies its operated position.

3, In direction selecting'means for a stretch of railway trackequipped'with a signaling system governed jointly by trafiic directionrelays at opposite ends of the stretch'so that at times the stretch isconditioned for traffic movements in traffic direction relays from acentral office and :3:'

for transmitting indication codes for indicating traffic conditions atsaid oiiice, in combination, electroresponsive means at said office fordesignating the direction for traffic movements and for controlling thetransmission of codes by said 4.:

means for restoring said auxiliary relay to its normal position inresponse to an indication code transmitted when a train enters thestretch,

occupancy indication means at said ofiice'which is operated when anindication is received that said stretch is occupied and is'restored toits normal'position when an indication is received that said stretch isunoccupied, and locking means at said control :ofiice'comprisingnormally closed contacts controlled by said auxiliary relay and saidoccupancy indication means in a circuit for controlling saidelectroresponsive.means, the opening of such contacts being effectivetomaintain the designated traflic direction by preventing theenergization of said electroresponsive -means when said auxiliary'relayor said occupancy indication means occupies its operatedposition.

4. In direction selecting'm'eans for a' stretch of railway trackequipped with asignaling system governed 'jointly by traffic directionrelays at opposite ends of "the stretch so that "at times the stretch isconditioned for 'traflic movements in one direction and at other timesfor trafiic movements in the opposite direction and having a signal ateach end for governing trailic movements into the stretch and a signalcontrol relay for each-signal for manuallygoverning the clearing thereofin accordance with the condition of 24 said signaling system, togetherwith a code type remote system for transmitting control codes forcontrolling the signal control and tralfic direction relays from acentral office and for transmitting indication-codes for indicatingtraffic conditions at said office, in combination, electroresponsivemeans at said ofiice for designating the direction for traffic movementsand for controlling-the transmission of codes by said remote controlsystem by which said trafiic direction relays are operated to establishthe corresponding direction for traffic movements in said stretch, afirst auxiliary relay at the oflice, means for operating said firstauxiliary relay in response to the transmission of a control code forclearing asignalby operation of its signalcontrol relay, a secondauxiliary relay, means effective only when said first auxiliary relayoccupies its operated position for operating said second auxiliary relayin-response to the transmission of a control code for putting a signalto stop by restoring its'signal control relay to normal, a signalindication relay for each signal, means responsive to the indicationcode transmitted'when a signal is clear for operating the correspondingsignal indication relay, means controlled by each signalindication-relay for restoring said first auxiliary relay to its normalposition when such indication relay is operated, means controlled bysaid second auxiliary relay for rendering any indication codetransmitted when said second auxiliary relay is in its operated positioneffective to restore said first and second auxiliary relays to theirnormal positions, and locking means at saidofiice comprising a normallyclosed contact of said first auxiliary relay in a circuit forcontrolling said electroresponsive means, the opening of such contactbeing effective to maintain the designated traffic direction bypreventing the energization of said electror-esponsive means when saidfirst auxiliary relay occupies its operated position.

5. In direction selecting means for a stretch of railway track equippedwith a signaling system governed jointly by traffic direction relays atopposite ends of the stretch so that at times the stretch is conditionedfor trafiic movements in one direction and at other times for trafficmovements in the opposite direction and having a signal at each end forgoverning traflic movements into the stretch and asignal control relayfor each signal for manually governing the clearing thereof inaccordance with the condition of said signaling system, together with acode type remote control system for transmitting control codesforcontrolling the signal control and traific direction relays from acentral office and for 'for operating said first auxiliary relay inresponse to the transmission of a control-codeforclearing a signal byoperation of its signal control-relay, a second auxiliary relay, meanseffective only when said first auxiliary relay occupies its operatedposition for operating said second auxiliary relay in response tothe'transmission of a control code for putting a signal to stop byrestoring its signal control relay to normal, a track in 25 dicationrelay for each end of the stretch, means responsive to the indicationcode transmitted when a train enters the stretch at either end foroperating the corresponding track indication relay, means controlled byeach track indication relay for restoring said first auxiliary relay toits normal position when such indication relay is operated, meansresponsive to an indication code transmitted when said second auxiliaryrelay is in its operated position for restoring said first and secondauxiliary relays to their normal positions irrespective of the conditionindicated by such code, occupancy indication means at said office whichis operated when an indication is received that saidstretch is occupiedand is restored to its normal position when an indication is receivedthat said stretch is unoccupied,and.

locking means at said oflic'e'comprising normally closed contactscontrolled by said first auxiliary relay and said occupancy indicationmeans in a circuit for controlling said electroresponsive means, theopening of such contacts being effective to maintain the designatedtraflic direction by preventing the energization of saidelectroresponsive means when said first auxiliary relay or saidoccupancy indication means occupies its operated position.

6. In direction selecting means for a stretch of railway track equippedwith a signaling system governed jointly by traffic direction relays atopposite ends of the stretch so that at times the stretch is conditionedfor trafiic movements in one direction and at other times for trafiicmovements in the opposite direction and having a signal at each end forgoverning traffic movements into the stretch and a signal control relayfor each signal for manually governing the clearing thereof inaccordance with the condition of said Signaling system, together with acode type remote control system for transmitting control codes forcontrolling the signal control and traffic direction relays from acentral ofiice and for transmitting indication codes for indicatingtraffic conditions at said ofiice, in combination, electroresponsivemeans at said ofiice for designating the direction for trafiic movementsand for controlling the transmission of codes by said remote controlsystem by which said trailic direction relays are operated to establishthe corresponding direction for trafiic movements in. said an indicationrelay at said office for each of said signals, each signal indicationrelay being operated when an indication is received that the aslays isin its operated position for restoring said auxiliary relay to itsnormal position, and looking means at said ofiice comprising normallyclosed contacts of said auxiliary relay and of said indication relays ina circuit for controlling said electrorespqnsive mea l fi p n 0f511,611,0011- 26 tacts being effective to maintain the designatedtrafiic direction by preventing the energization of saidelectroresponsive means when saidauxiliary relay or either of saidsignal indication relays occupies its operated position.

'7. In direction selecting means for a stretch of railway track equippedwith a signaling system governed jointly by traffic direction relays atopposite ends of the stretch so that at times the stretch is conditionedfor trafiic movements in one direction and at other times for trafiicmovements in the opposite direction and having a signal at each end forgoverning traffic movements into the stretch and a signal control relayfor each signal for manually governing the clearing thereof inaccordancewith the condition of said signaling system, together with acode type remote control system for transmitting control codes forcontrolling thev signal control and traffic direction relays from acentral ofiice and for transmitting indication codes for indicatingtraffic conditions at said office, in combination, electroresponsivemeans at said ofiice for designating the direction for traffic movementsand for con-, trolling the transmission of codes by said remote;

indication is received that the associated signal is clear and beingrestored to its normal position when an indication is received that theassociated signal is at stop, means at the office efiec-.

tive when said auxiliary relay is in its operated position and a controlcode is transmitted for putting a signal to stop by restoring its signalcontrol relay to normal for, causing the signal indicatiomrelay for suchsignal to assume its operated position concurrently with thetransmission of such control code, means responsive to the indicationcode transmitted when a train enters said signal indicationrelays is inits operated position for restoring said auxiliary relay to its normalposition, and locking means at said ofiice comprising normally closedcontacts of said auxiliary relay and of said signal indication relays ina circuit for controlling said electroresponsive means, the opening ofsuch contacts being effective to maintainthedesignated trafificdirection by preventing the energization of said electroresponsive meanswhen said auxiliary relay or either of said signal indication relaysoccupies its operated. position.

8. In direction selecting means for a stretch of railway track equippedwith a signaling sys tem governed jointly by trafiic direction relays atopposite ends of thestretch so that at-times the'stretch is conditionedfor trafiic movements in one direction and at other times for trafficmovements in the opposite direction and having a signal at each end forgoverning traffic movements into the'stretch and a signal control re' 7lay for each signal for manually governing the clearing thereof inaccordance with the condition of said signaling system, together with acode type remote control system for transmitting control codes forcontrolling the signal cone 27 trol and trafiic direction relays from acentral oilice and for transmitting indication codes for indicatingtrafiic conditions at said oflice, in combination, a signal controllever at the oilice for each of said signals, each of said levers oeingmovable between a clear and a stop position, electroresponsive means atsaid ofiice for designating the direction for trailic movements and forcontrolling the transmission of codes by said remote control system bywhich said traffic direction relays are operated to establish thecorresponding direction for traiiic movements in said stretch and foralso governing jointly with said signal control levers the transmissionof codes by said remote control system by which said signal controlrelays are operated to clear said signals, an auxiliary relay at theoflfice, means for operating said auxiliary relay in response to thetransmission of a control code provided such code is transmitted whenthe control lever for the signal at the end of the stretch which saidelectroresponsive means designates to be the entrance end is in itssignal clear position, an indication relay at said office for each ofsaid signals, each signal indication relay being operated when anindication is received that the associated signal is clear and beingrestored to its normal position when an indication is re ceived that theassociated signal is at stop, means responsive to the indication codewhich is transmitted when a signal is cleared for restoring saidauxiliary relay to its normal position, and locking means at said oiiicecomprising normally closed contacts of said auxiliary relay and of saidsignal indication relays in a circuit for controlling saidelectroresponsive means, the opening of such contacts being effective tomaintain the designated trafiic direction by preventing the energizationof said electroresponsive means when said auxiliary relay or either ofsaid signal indication relays occupies its operated position.

9. In direction selecting means for a stretch of railway track equippedwith a signaling system governed jointly by trailic direction relays atopposite ends of the stretch so that at times the stretch is conditionedfor trafiic movements in one direction and at other times for traincmovements in the opposite direction and having a signal at each end forgoverning traffic movements into the stretch and a signal control relayfor each signal for manually governing the clearing thereof inaccordancewith the condition of said signaling system, together withv a code typeremote control system for transmitting control codes for controlling thesignal control and trafiic direction relays from a central office andfor transmitting indication codes for indicating trafiic conditions atsaid oiiice, in combination, a signal control lever at the ofiice foreach of said signals, each of said levers being movable between a clearand a stop position, electroresponsive means at said office fordesignating the direction for traffic movements and for controlling thetransmission of codes by said remote control system by which saidtraffic direction relays are operated to establish the correspondingdirection for traflic movements in said stretch and for also governingjointly with said signal control levers the transmission of codes bysaid. remote control system by which said signal control relays areoperated to clear said signals, an auxiliary relay at the office, meansfor operating said auxiliary relay in response to the transmission of acontrol code provided such code is transmitted when the control leverfor the signal at the end of the stretch. which said electroresponsivemeans designates to be the entranceend. is in its signal clear position,means responsive to the indication code which is transmitted whena trainenters the stretch for restoring, said auxiliary relay to its normalposition, occupancy indication. means at said office which is operatedwhen an indication is received that said stretch is occupied and isrestored to its normal position when an indication is received. thatsaid stretch is unoccupied, and locking means at said office comprisingnormally closed contacts controlled by said auxiliary relay and saidoccupancy indication means in a circuit for controlling saidelectroresponsive means, the opening of such contacts being effective tomaintain the designated traffic direction by preventing the energizationof said electroresponsive means. when said auxiliary relay or saidoccupancy indication means occupies its operated position.

10. In direction selecting means for a stretch of railway-track equippedwith a signaling sys temgoverned jointly by trafiic direction relays atopposite ends of the stretch so that at times the stretch is conditionedfor traiiic movements in one direction and at other times for traflicmovements in the opposite direction and having a signal at each end forgoverning traffic movements into the stretch and a signal control relayfor each signal for manually governing the clearing thereof inaccordance with the condition of said signaling system, together with acode type remote control system for transmitting control codes forcontrolling the signal control and trafiic direction relays from acentralofiice and for transmitting indication codes for indicatingtrafic conditions at said oiiice, in combination, a signal control lever"at the oifice for each of said signals, each of said levers beingmovable between a clear and a stop position, electroresponsive means atvsaid office for designating the direction for trafiic movements and forcontrolling the transmission of codes by said remote control system bywhich said traffic direction relays are operated to establish thecorresponding direction for traffic movements in said stretch and foralso governing jointly with said signal control levers the transmissionof codes by said remote control system by which said signal controlrelays are operated to clear said signals, an auxiliary relay at theoilice, means for operating said auxiliary relay in response to thetransmission of a control code provided such code is transmitted whenthe control lever for the signal at the end of the stretch which saidelectroresponsive means designates to be the entrance end is in itssignal clear position, means responsive to the indication code which istransmitted when a signal is cleared for restoring said auxiliary relayto its normal position, an indication relay at said oilice for each ofsaid signals, each signal indication relay being operated when anindication is received that the associated signal is clear and beingrestored to its normal position when an indication is received that theassociated signal is at stop, a circuit at said ofiice governed by saidsignal control levers for operating said electroresponsive means tochange the designated trafiic direction, and locking means in saidcircuit comprising contacts of said auxiliary relay and of said signalindication relays which are closed only when said auxiliary relay andsaid signal indication relays occupy their normal positions.

.11. In direction selecting means for a stretch of railway trackequipped with a signaling system governed jointly by trafiic directionrelays at opposite ends of the stretch so that at times the stretch isconditioned for traffic movements in one direction and at other timesfor trafiic movements in the opposite direction and having a signal ateach end for governing traffic movements into the stretch and a signalcontrol relay for each signal for manually governing the clearingthereof in accordance with the condition of said signaling system,together with a code type remote control system for transmitting controlcodes for controlling the signal control and trafiic direction relaysfrom a central office and for transmitting indication codes forindicating traffic conditions at said ofiice, in combination, a signalcontrol lever at the office for each of saidsignals, each of said leversbeing movable between a clear and a stop position, electroresponsivemeans at said ofiice for desighating the direction for traffic movementsand for controlling the transmission of codes by said remote controlsystem by which said traffic direction relays are operated to establishthe corresponding direction for traffic movements in said stretch andfor also governing jointly with said signal control levers thetransmission of codes by said remote control system by which said signalcontrol relays are operated to clear said signals, an; auxiliary relayat the office, means for operating said auxiliary relay in response tothe transmission of a control code provided such code is transmittedwhen the control lever for the signal at the end of the stretch whichsaid electroresponsive means designates to be the entrance end is in itssignal clear position, means responsive to the indication code which istransmitted when a train enters the stretch for restoring said auxiliaryrelay to its normal position, occupancy indication means at said ofiicewhich is operated when an indication is received that said stretch isoccupied and is restored to its normal position when an indication isreceived that said stretch is unoccupied, a circuit at said officegoverned by said signal control levers for operating saidelectroresponsive means to change the designated traffic direction, andlocking means in said circuit comprising contacts controlled bysaidauxiliary relay and said occupancy indication means wihch are closedonly when said auxiliary relay and said occupancy indication meansoccupy their normal positions.

12. In direction selecting means for a stretch of railway track equippedwith a signaling system governed jointly by trafiic direction relays atopposite ends of the stretch so that at times the stretch is conditionedfor trafiic movements in one direction and at other times for trafiicmovements in the opposite direction and having a signal at each end forgoverning traihc movements into the stretch and a signal control relayfor each signal formanually governing the clearing thereof in accordancewith the condition of said signaling system, together with a code typeremote control system for transmitting control codes for controlling thesignal control and traffic direction relays from a central ofiice andfor transmitting indication codes for indicating trafiic conditions atsaid ofiice, in combination, a signal control lever at the ofiice foreach of said signals, each of said levers being movable between. a clearand a stop position, electroresponsivemeans at said' office fordesignatin the direction for traffic movements and for controlling thetransmission of codes jointly with said signal control levers thetransmission of codes by said remote control system by which said signalcontrol relays are operated to clear said signals, a first auxiliaryrelay at the ofiice, means for operating said first auxiliary relay inresponse to the transmission of a control code provided such code istransmitted when the control lever for the signal at the end of thestretch which said electro-responsive means designates to be theentrance end is in its signal clear position, a second auxiliary relay,means for operating said second auxiliary relay in response to thetransmission of a con trol code provided such code is transmitted whensaid first auxiliary relay occupies its operated position and thecontrol lever for the signal at the end of the stretch which saidelectroresponsive means designates to be the entrance end is in its stopposition, means responsive to the indication code transmitted when atrain enters the stretch for restoring said first auxiliary relay to itsnormal position, means controlled by said second auxiliary relay forrendering any indication code transmitted when said second auxiliaryrelay is in its operated position effective to restore said first andsecond auxiliary relays to their normal positions, and

locking means at said oflice comprising a nor-' mally closed contact ofsaid first auxiliary relay in a circuit for controlling saidelectroresponsive means, the opening of such contact being effective tomaintain the designated traffic direction by preventing the energizationof said electroresponsive means when said first auxiliary relay occupiesits operated position.

13. In direction selecting means for a stretch of railway track equippedwith a signaling system governed jointly by trafiic direction relays atopposite ends of the stretch so that at times the stretch is conditionedfor trafiic movements in one direction and at other times for trafiicmovements in the opposite direction and having 7 a signal at each endfor governing traflic movements into the stretch and a signal controlrelay for each signal for manually governing the clearing thereof inaccordance with the condition of said signaling system, together with acode communication system of centralized control including a fieldstation for each end of the stretch for controlling the signal controland traffic direction relays from a central ofiice and for indicatingtrafiic conditions at said ofiice, in combination, electroresponsivemeans at said office for designating the direction for traffic movementsand for controlling thetransmission of codes by said remote controlsystem to said field stations by which said trafiic direction relays areoperated to establish the corresponding closed contact of said auxiliaryrelay in a circuit for controllingi'said electroresponsive-means, theopening of said contact being effective to maintain the designatedtraific direction when said auxiliary relay occupies its operatedposition 14. In directionselecting means for a stretch of railway trackequipped with a signaling system. governed jointly by trafiic directionrelays at opposite ends of the stretch so that at times the stretch isconditioned for trafiic movements in one direction and at other timesfor trafiic movements in the opposite direction and having a signal ateach end for governing traffic movements into the stretch and-a signalcontrol relay for each signal for manually governing the clearing.thereof in accordance with the condition of said signaling system,together with a code communication system of centralized controlincluding a field station for each end of the stretch for i controllingthe signal control and traffic direction relays from a central ofiiceand for indicating traffic conditions at said office, in combination,electroresponsive means at said office for designating the direction fortrafiic movements and for controlling the transmission of codes by saidremote control system to said field stations by which said trafiicdirection relays are operated to establish the corresponding directionfor traffic movements in said stretch, an auxiliary relay at saidoffice, means for operating said auxiliary relay in response to thetransmission of a control code, provided such code is one for operatinga signal control relay to clear a signal at a field station at one endof the stretch, another relay at the ofiice, means for operating saidother relay in response to the transmission of another control code tosaid field station, provided such other control code is transmitted whensaid auxiliary relay occupies its operated position and is one forrestoring said signal control relay to normal to put the associatedsignal to stop,.means for restoring said auxiliary relay to its normalposition in response to the transmission of an indication code from saidfield station to the office showing that a train has entered thestretch, means effective only when said other relay is in its operatedposition for restoring said auxiliary relay to its normal position inresponse to the transmission of an indication code from said fieldstation to the office irrespective of the character of such code, andmeans at said otfice comprising a normally closed contact of saidauxiliary relay in a circuit for said electroresponsive means theopening of such contact being efiective to maintain the designatedtraffic direction by preventing the energization of saidelectroresponsive means when said auxiliary relay occupies its operatedposition.

15. In direction selecting means for a stretch of railway track equippedwith a signaling system governed jointly by trafiic direction relays atopposite ends of the stretch so that at times the stretch is conditionedfor trafiic movements in one direction and at other times for trafficmovements in the opposite direction and having a signal at each end forgoverning trafiic movements into the stretch and a signal control relayfor each signal for manually governing the clearing thereof inaccordance with the condition of said signaling system, together with acode communication system of centralized control including a fieldstation for each end of the stretch for controlling the signal controland trafiic directionrelays from a central oiiice and for indicatallmunication system including at the ofiice a delivery relay for each ofsaid field stations, each of said delivery relays being operatedtemporarily during receipt of an indication code from the associatedfield station, in combination, electroresponsive means at said officefor designating the direction for trafiic movements and for controllingthe transmission of codes to said field stations by said remote controlsystem by which said trafiic direction relays are operated to establishthe corresponding direction for trafiic movements in said stretch, anauxiliary relay at said ofiice, means for operating said auxiliary relayin response to the transmission of a control code provided such code isone for operating a signal control relay to clear a signal at a fieldstation at one end of the stretch, another relay at the office, meansfor operating said other relay in response to the transmission ofanother control code to said field station, provided such other controlcode is transmitted when said auxiliary relay occupies its operatedposition and is one for restoring said signal control relay to normal toput the associated signal to stop, a first means for restoring saidauxiliary relay to its normal position rendered eilective upon thereception of an indication code from said field station at the ofiiceshowing that a train has entered the stretch, a second means forrestoring said auxiliary relay to its normal position, said second meansbecoming efiective when said other relay and the delivery relay are bothoperated, and means at said ofiice comprising a normally closed contactof said auxiliary relay in a circuit for said electroresponsive means,the opening of such contact being effective to maintain the designatedtrafiic direction by preventing the energization of saidelectroresponsive means when said auxiliary relay occupies its operatedposition.

16, In locking means for a stretch of railway track equipped with asignaling system governed by trafiic control means so that at times thestretch is conditioned for traffic governed by a first signal and atother times is conditioned for trafiic governed by a second signal andhaving signal control means for manually controlling the clearing ofsaid signals in accordance with the condition of said signaling systemtogether with a code type communication system for controlling saidsignal and trafiic control means from a remote oifice and for indicatingtraffic conditions at said ofiice, in combination, electro responsivemeans at said o ifice controlling the transmission of codes by saidremote control system by which said trafiic control means is operated toprepare the stretch for trafiic governed by said first or said secondsignal and for designating at the ofiice. whether tramc governed by saidfirst or said second signal may move in said stretch, an auxiliary relayat the office, means for operating said auxiliary relay in response tothe transmission of a control code provided such code is one forclearing a signal by operation of said signal control means, means forrestoring said auxiliary relay to its normal position in response to anindication code transmitted when a train enters the stretch, and meansat said ofiice efiective only when said auxiliary relay occupies itsnormal position for operating said electroresponsive means to select thedirection for trafiic movements in said stretch.

17. In locking means for a, stretch'of railway

